I would expect it to make very little difference... Obviously yes when you do it to the turbocharger out of the car and you point your air line at the turbine/compressor, it spools up quick - however the turbocharger was stopped to begin with and if you keep on the air line, it doesn't get much better. Also think about what happens when you attach a boost hose to it and start actually compressing... The actual amount of energy being transferred into the rotating assembly is frankly sweet FA unless you're dumping a LARGE amount of air in!

As has been mentioned previously - think of ways to increase exhaust gas energy...

All IMHO of course.

I just wanted to post an update to this:

After running some tests with a journal bearing GTX3582R knock off, the compressed air with various nozzles ranging from 1/16" to 5/16" @ 120 psi just didn't generate enough rpm on the turbo.    I'm talking < 5k rpm.  

So I've ended up bagging the idea.   Perhaps with a ball bearing turbo of GT30 sized turbine would show some results.

I ended up going with a 12.8:1 compression ratio on this build for running 50% or larger ethanol content fuel and I expect to have much more noticable throttle response under all conditions.

Results will be posted in the vehicles section soon.